A simple model of longitudinal digital magnetic recording

A two-dimensional theoretical distribution with many of the features observed on a 5000 :1 model is developed and the field external to the medium linking the replay head is shown to be equivalent to the field from a filamentary pole parallel to the medium surface and transverse to the track direction located at the centre of each transition. Each transition is described by s pole strength per unit track width, tand its distance behindthe medium surface, a. Methods for relating and a to the magnetic characteristic and physical dimensions of themedium are developed. Prediction of the replay performance from the theory show good agreement with experimental data. A notation for describing vectorial magnetization in two cartesian dimensions is introduced which automatically enforces the requirement that the divergence of B is zero whilst simultaneously allowing the magnetization of elements within the distribution some independence so that internal divergence of magnetization is described.